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6611837: block frequency is zero

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Insert_goto_at should set frequency for newly created blocks

Reviewed-by: never
This commit is contained in:
Chuck Rasbold 2008-08-28 10:22:12 -07:00
parent 8ab0a4d7a9
commit bdd62705f2
2 changed files with 30 additions and 1 deletions
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6
hotspot/src/share/vm/opto/block.cpp
View file

@ -467,6 +467,10 @@ void PhaseCFG::insert_goto_at(uint block_no, uint succ_no) {
// get successor block succ_no
assert(succ_no < in->_num_succs, "illegal successor number");
Block* out = in->_succs[succ_no];
// Compute frequency of the new block. Do this before inserting
// new block in case succ_prob() needs to infer the probability from
// surrounding blocks.
float freq = in->_freq * in->succ_prob(succ_no);
// get ProjNode corresponding to the succ_no'th successor of the in block
ProjNode* proj = in->_nodes[in->_nodes.size() - in->_num_succs + succ_no]->as_Proj();
// create region for basic block
@ -491,6 +495,8 @@ void PhaseCFG::insert_goto_at(uint block_no, uint succ_no) {
}
// remap predecessor's successor to new block
in->_succs.map(succ_no, block);
// Set the frequency of the new block
block->_freq = freq;
// add new basic block to basic block list
_blocks.insert(block_no + 1, block);
_num_blocks++;

25
hotspot/src/share/vm/opto/gcm.cpp
View file

@ -1609,7 +1609,30 @@ void CFGLoop::compute_freq() {
float Block::succ_prob(uint i) {
int eidx = end_idx();
Node *n = _nodes[eidx]; // Get ending Node
int op = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : n->Opcode();
int op = n->Opcode();
if (n->is_Mach()) {
if (n->is_MachNullCheck()) {
// Can only reach here if called after lcm. The original Op_If is gone,
// so we attempt to infer the probability from one or both of the
// successor blocks.
assert(_num_succs == 2, "expecting 2 successors of a null check");
// If either successor has only one predecessor, then the
// probabiltity estimate can be derived using the
// relative frequency of the successor and this block.
if (_succs[i]->num_preds() == 2) {
return _succs[i]->_freq / _freq;
} else if (_succs[1-i]->num_preds() == 2) {
return 1 - (_succs[1-i]->_freq / _freq);
} else {
// Estimate using both successor frequencies
float freq = _succs[i]->_freq;
return freq / (freq + _succs[1-i]->_freq);
}
}
op = n->as_Mach()->ideal_Opcode();
}
// Switch on branch type
switch( op ) {